I have imported an excel file to eviews, I have added more data and want to import the file again but it tells me 'repeated values found in source id series'. How can I get rid of the previous file and import the new file.

You get rid of the old file by just ignoring it. Just import into a new workfile. The issue of repeated ids is more problematic. You can't have an id repeated (how would EViews know which observation is which?), so you may want to bring the file in as unstructured.